What is CVE-2018-20859?

CVE-2018-20859 is a medium-severity vulnerability in Edx Edx-Platform, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2019-07-30.

How severe is CVE-2018-20859?

Medium severity. CVSS v3 base score is 6.1 out of 10.

XSS in Edx Edx-Platform

CVE-2018-20859

edx-platform before 2018-07-18 allows XSS via a response to a Chemical Equation advanced problem.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2019-07-30 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.012 (67.0th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 67th percentile — 67.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.012 · newest: 0.012 · change: 0.000

Affected products

Edx Edx-Platform

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

groups.google.com/forum/
github.com/edx/edx-platform/commit/5b144559fbdba7ff673cc1c165aa2d343e07b6bd.pat… (Patch, Third Party Advisory)
patch-diff.githubusercontent.com/raw/edx/edx-platform/pull/18639.patch (Patch, Third Party Advisory)

Frequently asked questions

What is CVE-2018-20859?: CVE-2018-20859 is a medium-severity vulnerability in Edx Edx-Platform, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2019-07-30.
How severe is CVE-2018-20859?: Medium severity. CVSS v3 base score is 6.1 out of 10.